A brief overview of technologies in known wireless networks is provided below.
Known wireless networks may comprise an Access Network Discovery and Selection Function, ANDSF, which is described for example in Chapter 4.8 of 3GPP specification 3GPP TS 23.402 v9.4.0 (March 2010) and 3GPP TS 24.302.
The packet core network and system referred to therein (Evolved Packet Core Network, EPC; Evolved 3GPP PS Domain, EPS) allows a UE to be provided, via the ANDSF, with policies for selecting access networks through which to connect to the packet core network (EPC).
The information provided by the ANDSF allows the UE to scan for access networks and to decide which access network to select among a plurality of access networks, based on data and policies.
Detailed background information of the current state of the art with respect to the ANDSF, and its interaction with UE(s), is provided below.
The ANDSF is a network element that contains data management and control functionality necessary to provide network discovery and selection assistance data in accordance with the operator(s) policy.
The introduction of an ANDSF does not impact on the attach procedures for any of the access operations. In particular, it does not interfere with the existing 3GPP PLMN selection mechanisms used for the 3GPP Access Technologies.
ANDSF defines a simple client-server architecture with single Access Network Info Request and Response messages. UEs may contact the ANDSF server by sending an Access Network Info Request message to it. The ANDSF server responds to the UE by sending an Access Network Info Response message.
In Access Network Info Response messages, the ANDSF provides two types of information: an inter-system mobility policy and access network discovery information.
With an inter-system mobility policy, an operator, or any other organization maintaining an ANDSF server, can affect which networks UEs are using.
For example, an inter-system mobility policy may contain a prioritized network list that advises the UE about a priority order in which it can consider access networks during the access network selection process. The inter-system mobility policies received from the ANDSF take precedence over those statically provisioned in the UE.
The UE can be configured in automatic or manual mode. In automatic mode, the UE may, at its discretion, accept policies and execute changes of access networks according to the received policies. In manual mode, the consent of the user is required prior to accepting a policy and executing it.
In the above known system, policies sent by the ANDSF are merely advice for selecting by the UE an access network, for example in case of roaming or handover.
Access network discovery information is intended to help the UE to discover networks in its neighborhood. For example, the access network discovery information may contain information on the network type, network ID, used radio frequency and channel. With this information, the UE may perform a network scan (i.e. discovery) more efficiently, since it does not need to go through all the possible access network technologies and frequency bands. By nature, the access network discovery information may be tied to a specific location and is also more short-lived than network selection information.
The ANDSF implements the S14 interface towards the User Equipment (UE). The interface is used to provide information on access networks available in the vicinity of the UE and information on operator's preference on these access networks. The S14 interface is implemented with OMA Device Management V1.2, OMA-ERELD-DM-V1—2—1, WAP Push OMA Push Architecture V2.3, OMA-AD-Push-V2—3-20091013-C, and a security mechanism that includes OMA DM bootstrap, secure HTTPS, IETF RFC 2616: Hypertext Transfer Protocol—HTTP/1.1, or GAA bootstrap, 3GPP TS 33.919: Generic Authentication Architecture (GAA); System description.
The information provided by the ANDSF is structured in a so-called OMA DM Managed Object, MO, according to what is specified in 3GPP TS 24.312. This will be referred to herein as an Access Network Discovery and Selection Function (ANDSF) Management Object (MO).
The UE and ANDSF S14 interface supports both a pull and a push mode. In pull mode the UE initiates the communication to retrieve the data. In push mode the ANDSF initiates the communication to send data to the UE.
In order for the UE to receive information from the ANDSF, the UE has to have IP connectivity and to have discovered the ANDSF. If the ANDSF needs to push data and the UE does not have IP connectivity, or has not discovered the ANDSF, the ANDSF can use WAP push to force the UE to trigger the process.
As shown in FIG. 1, the ANDSF can be located in a Home network, H-ANDSF 1002, or in a Visited network, V-ANDSF 1003.
For a UE 1001 that is roaming, it is possible that the UE 1001 acquires data from both the H-ANDSF 1002 and V-ANDSF 1003. In any case, the H-ANDSF 1002 and V-ANDSF 1003 do not have an interface between them. The interface specified between the UE 1001 and any of the H-ANDSF 1002 or V-ANDSF 1001 is the S14 interface.
The UE 1001 can also be statically provisioned with intersystem mobility policy and access network discovery information. In case the UE 1001 also acquires the same type of information from the network, the information acquired from the ANDSF has precedence over statically provisioned information in the UE 1001.
FIG. 2 shows a general information flow demonstrating signaling for both push and pull operation modes. The ANDSF 2002, at any time, can decide to push policy rules and discovery information to the UE 1001, using, for instance, WAP Push, as in step 201. The next steps are common for both push and pull modes. In step 202, the UE 1001 attaches its location information and requests the ANDSF 2002 to send the policy rules and discovery information. In step 203, the ANDSF 2002 filters the policy rules and discovery information according to the current location of the UE 1001 and then sends this filtered policy rules and discovery information to the UE 1001. Then the UE 1001 may need to switch new interfaces on or off, to try to attach to a new network (step 204), according to the information received from the ANDSF 2002. Eventually, the UE 1001 will attach to the new access network (step 205).
ANDSF 2002 is the node that manages two types of information: intersystem mobility policy and access network discovery information. Additionally, the UE 1001 is able to send to the ANDSF 2002 its UE current location.
An intersystem mobility policy is a set of operator-defined rules and preferences that affect the intersystem mobility decisions taken by the UE 1001. Therefore, intersystem mobility policies provide the UE 1001 with the means to prioritize the access network used by the UE 1001.
The access network discovery information merely provides the UE 1001 with additional information that helps the UE 1001 to gain access to the access network defined in the policy.
The ANDSF 2002 merely provisions the UE 1001 over the S14 interface with information policies for selecting access networks, wherein the final decision relies on information configured in the UE, and/or in decisions made by the UE's user.
The ANDSF MO contains three big chunks of data:                Inter-system Mobility Policy Rules: Composed of several conditions, including access network types (e.g. 3GPP, 3GPP2, WLAN, WiMAX), access network identifiers (e.g. PLMN, TAC. RAC, BSSID, etc), validity areas and time frames, among others, and a priority. The highest priority matched rule determines the access to be selected by the UE 1001.        Discovery Information: The discovery information data provides the UE 1001 with suitable data for helping in the discovery of access networks. This data contains the type of access network for which discovery information is provided (e.g., 3GPP, 3GPP2, WLAN, WiMAX); the access network area (e.g. PLMN, TAC, NAP-ID, BSSID, etc); and additional information on the specific access network.        UE location: The UE current location provides a placeholder for the UE 1001 to provide its current location to the ANDSF 2002, in terms of access network parameters or geographical location. This is used to filter the irrelevant data for the current location of the UE 1001.        
The discussion of known access network technologies continues below where the provision of data communication to a terminal is generally considered.
The increasing demand for data communication, such as wireless IP connectivity, has reached a level where it is possible for demand to exceed the capacity of an access network.
Some access network technologies, such as traditional GSM/GPRS, are, due their insufficient bandwidth, unable to provide an acceptable level of performance when the demand for data communication is high.
EDGE, W-CDMA, HSDPA and HSUPA technologies may provide an improved bandwidth, but they are also unable to cope with a high demand for data communication. LTE and its E-UTRAN with OFDMA and SC-FDMA technology may be able to provide a further increase in bandwidth. Other existing technologies, such as WLAN and WiMAX also try to meet the demand for high-bandwidth IP flows.
However, no known networks are currently capable of reliably meeting the largest demands for high bandwidth data communication. The high demand may be caused by, for example, the need to provide data connectivity to multiple users at the same time.
The above problem is expected to worsen as demand for data communication increases further.
In order to mitigate the above problem, operators have deployed multiple technologies for providing access to data networks (e.g., IP data networks such as the Internet) are there are known UEs capable of supporting multi-technology connectivity.
Although known UEs may implement multiple access network technologies and thereby provide connectivity through a variety of access networks, at the time of establishing a data communication, it is the user of the UE who selects an access network out of those available through the different technologies implemented in the UE device.
For example, the user may select a cellular access network (e.g. traditional GSM/GPRS, or LTE) or a WLAN access network when trying to connect to the Internet. If the selected access network suffers from a degree of congestion that prevents the service (e.g., connection to the Internet or establishment of a multimedia session) from being provided, the connection attempt to the IP data network fails and the user of the UE is not provided with the desired service.
In particular, when a UE device demands a certain Quality of Service when it is establishing data communication for a service, if the demand cannot be met, the UE device is required to limit its behavior to notify this (failure) event to the user. For example, an error message may be displayed to the user of the UE.
In short, regardless of the bandwidth that can be provided by an access network or multiple access network technologies, it is always possible that a UE will have its requested service rejected due to a lack of available resources in the access network that currently provides the UE with data connectivity (e.g. due to congested and/or unavailable nodes, the bandwidth required by the service cannot or should not be provided/guaranteed, etc).
However, the UE is not aware of this before requesting a service, and informing all of the UEs connected to an access network(s) with the network status of the network(s) is cumbersome, resource consuming, and may even be counterproductive (e.g. in the case that an access network is already congested, or close to congestion).
As a result, the user of a UE does not receive a requested service and has to manually select an alternative access network (e.g. using access network information provided by the UE).
Moreover, since the selected alternative access network may also be undergoing a congestion situation, the above problem of not receiving a requested service may be encountered by the user again.